class Solution {
    public:
        int uniquePathsWithObstacles(vector<vector<int>>& obstacleGrid) {
            int n = obstacleGrid[0].size();
            int m = obstacleGrid.size();
            if (obstacleGrid[0][0] == 1) {
                return 0;
            }
            vector<vector<int>> dp(obstacleGrid);
            for (int i = 0; i < m; i++) {
                if (obstacleGrid[i][0] == 1) {
                    for (int j = i; j < m; j++) {
                        dp[j][0] = 0;
                    }
                    break;
                } else {
                    dp[i][0] = 1;
                }
            }
            for (int i = 0; i < n; i++) {
                if (obstacleGrid[0][i] == 1) {
                    for (int j = i; j < n; j++) {
                        dp[0][j] = 0;
                    }
                    break;
                } else {
                    dp[0][i] = 1;
                }
            }
    
            for (int i = 1; i < m; i++) {
                for (int j = 1; j < n; j++) {
                    if (obstacleGrid[i][j] == 1) {
                        dp[i][j] = 0;
                    } else {
                        dp[i][j] = dp[i - 1][j] + dp[i][j - 1];
                    }
                }
            }
            return dp[m - 1][n - 1];
        }
    };